Cooled rim on cyanide pots



March 19, 1929. c. H. CARPEI qTE-IR ET AL 1,705,714

COOLED RIM ON C YANIDE POTS Filed June 4, 1927 INVENTO R5(hens/005467400719 A'TTORNEY Patented Mar. 19, 1929.

GRANSTON E. CARPENTER AND ALVIN I).

KEENE, OF MANSFIELD, OHIO, ASSIGNORS TO WESTINGHOUSE ELECTRIC ANDMANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

Application filed June 4,

creeping will continue until the salt sufficient- I 1y cools to freezeor crystallize. As a result,

. the top of the furnace becomes covered with the salt, and the moltensalt also follows the outer surface of the crucible and drops down intothe heating chamber, resulting in inju to the electrical resistor.

An object of our invention, therefore, is

to provide, in a salt-bath furnace, means for freezing or solidifyingthe molten salt at a desired point in the creepage path thereof toprevent injury and contamination of adjacent furnace parts.

In practicing our invention, we provide a salt-bath furnace of the usualtype with means for cooling the molten salt adjacent to the rim of thecontaining crucible, thereby causing the freezing of the salt thereon,and preventing the creeping thereof beyond said rim. Y

In the drawings;

Fig.1 is an elevation, partly in section and partly broken away, of asalt-bath furnace embodying our invention, and

Fig. 2 1s a view, in vertical section, of a portion of a furnaceembodying a modification of our device.

Referring more particularly to Fig. 1, a furnace embodying our inventioncomprises a substantially cylindrical metallic shell 2 provided with a:metallic bottom plate 4. The shell is lined with a plurality of layersof built-up refractory heat-insulating material 6, defining a heatingchamber 8. Resting upon the upper face of the refractory wall 6 is anannular plate 10 of heat-resistant material from which is suspended aplurality of sets of electric insulating blocks 12 which support andinsulate from each other the convolutions of an electrical resistanceelement l4, wound in the form of a double helix. The terminals of theresistor 14 are led through the refractory wall 6 and shell 2 COODED RIMON GYANIDE POTS.

1927. Serial 110.1%,511,

to a terminal box 15, secured to the shell 2, to facilitate theelectrical connection of the resistor to a suitable source of energy.The furnace structure is covered by an annular cast metallic plate 16secured, at its outer periphery, to the shell 2 and formed at its innerperiphery with an upturned head which cooperates with a down-turned beadformed on the outer periphery of an annular plate '18, which is co-axialwith plate 16.

The inner periphery of plate 18 is formed with an up-turned bead toco-operate in supporting relation with the out-turned rim 20 of acrucible 22.

The engagement of plate 18 with the rim 20 of the crucible is such as topermit of free radial expansion of the elements, and to perniit the freecirculation of air beneath and behind the rim 20. The rim 20 is formedunusually wide to provide a considerable area beyond the contact withthe upturned bead of plate 18.

The crucible 22 contains the salt utilized in heat treating (not shown),which, in the present instance is a. cyanide.

In the modification shown in Fig. 2, we have adapted the principle ofour invention to a salt-bath furnace of a larger size. In this case, thefurnace wall is built up of refractory bricks 3O surrounded by ametallic shell 32, having a sinuous electrical resistor 34 supportedupon the inner face thereof. A- crucible 36 for containing the moltensalt is provided with\a relatively wide and flat flange 38 whichissupported upon the top of the refractory wall.

Adjacent to the peripheral edge of flange 38 is a conduit 40 embedded ina mass 42 of fire-clay or other suitable cement. A plate 44 covers theconduit 40 and extends a short distance over the outer portion of theflange 38. A cooling fluid is circulated through conduit 40 and eflectsthe cooling of the adjacent areasof plates 38 and 44.

The operation of both forms of our device is substantially the same. InFig. 1, the molten salt will creep up the inner walls of the crucibleand over the out-turned rim 20. The temperature differential, however,between the outer portion of rim 20 and the walls of crucible 22 issuflicient to cause the cooling of the molten salt to a point where itwill solidify upon the rim. When a considerable amount of the salt hasbeen solidified, it may be chipped or scraped OK. In Fig. 2, the saltwill creep out of the crucible and over flange 38 until it reaches therelatively cool outer rim thereof where it will solidify.

Quite obviously, the particular design and construction of the furnacemay be varied considerably and still be within the scope of ourinvention. So far as the operation and function of the invention areconcerned, it is practically immaterial what source of heat is employed,but it is particularly advantageous when employing an electricalresistor, as shown, because of the deleterious effect of the creepingsalt thereon.

Also, while We have shown and described a salt-bath heat-treatingfurnace, my inven-- tion is applicable to a vessel containing any liquidwhich tends to creep beyond the rim thereof and which may be solidifiedthereupon by an appropriate change in the temperature thereof.

By our invention we have provided an efficient and economical means forpreventing contamination and injury of furnace parts incident to thecreeping of molten salt out of a containing crucible. v

Modifications may be made in our invention without departing from the sirit and scope thereof, and we desire, there ore, that only suchlimitations shall be placed thereon as are imposed by the prior art andare set forth in the appended claims.

We claim as our invention:

1. In a heat-treating furnace, the combination with a cruciblefor-containing a salt which creeps when in a molten state, of means forartificially cooling said crucible adjacent rim to effect thesolidification thereon of molten salt creeping out of said crucible.

3. In a heat-treating furnace, the combination with a. crucible adaptedto contain a molten salt bath and having a relatively Wide out-turnedrim, of means permitting the circulation of air beneath said rim toeffect the cooling thereof and the consequent solidification thereon ofvmolten salt creeping out of said crucible. I

4. In an electric heat-treating furnace, the combination with a cruciblefor containing a material which creeps when in a molten state responsiveto capillary action of means for preventing said molten material fromcreeping beyond the rim of said crucible comprising n eans forartificially cooling said rim to cause the crystallization orsolidification thereupon of the molten material.

5. The combination with a crucible containing a liquid which tends tocreep beyond the rim thereof responsive to capillary action, of meansfor solidifying said creeping liquid upon the rim of said cruciblecomprising means for effecting a rim temperature at which said liquidsolidifies.

In testimony whereof, we have hereunto subscribed our names this 27 dayof May, 1927.

CRANSTON H. CARPENTER. -ALVIN D, KEENE.

